Many people find it difficult to effectively braze two pieces of metal together. With preparation and forethought, however, it becomes quite easy indeed.
The first step in brazing two pieces of metal together involves acquiring a pair of tinted goggles rated for working with an oxy-acetylene torch, a flame and heat resistant workspace, a sparker, a pair of tongs, an oxy-acetylene torch, a high-pressure oxygen cylinder, and a moderate-pressure acetylene cylinder. The gas cylinders must be equipped with reliable pressure regulators, as well as gauges to report tank pressure and regulator pressure. In addition to all of the above materials, you will need a supply of brazing sticks; these are long sticks of flux coated metal that you will actually braze with. SAFETY NOTE: Brazing should always be done under a fume hood or in open air.
After obtaining your materials, you want to prepare your workspace, pieces of metal, and brazing sticks. Lie the metal pieces to be joined next to each other. Move them into position such that they are in perfect alignment with each other. If you have already used your workspace and it is hot, use your tongs to do this.
At this point, the next step is to light the torch. Turn the knobs on the gas cylinders until the cylinder pressure gauges go up as high as they will go. SAFETY NOTE: Do not over-open the knobs on the cylinders. In the case of a fire, you want to be able to shut off the gas flow as quickly as possible. Next, adjust the regulators on each cylinder, paying attention to the regulator pressure gauges to get the desired pressure. The pressures needed to braze with different metals differ, but the ratio of oxygen to acetylene should always be 2 to 1. To use bronze, a common brazing material, the acetylene regulator should be set for 5 psi and the oxygen for 10 psi. At this point, ensure that the gas flow knobs on your torch are clicked into the fully closed position. Now, open the acetylene knob the tiniest bit to release a trickle of gas. Take a sparker and use it to light the acetylene. You should have about a one-centimeter yellowish flame that sends off a black smoke. SAFETY NOTE: Never point a lit torch at yourself, others, inflammable materials, the gas cylinders, or the hoses that lead from the gas cylinders to the torch.
Now that you've got a tiny sputtering flame, you're going to increase it to the point where you can use if for brazing. SAFETY NOTE: At this point, your goggles should be over your eyes. The torch's flame can get quite bright and do damage to your eyes. Slowly increase the amount of acetylene released through the torch's nozzle. Don't do this too quickly or the flame will go out. Stop when the ends of the flame take on a feathery, ragged appearance. Cut back the acetylene until the raggedness just disappears. Now, very slowly open the oxygen valve on the torch. At first the flame will take on a whitish bluish appearance; keep turning up the oxygen until you can see a shrinking blue cone inside your flame. Open the oxygen valve until the blue cone is about a centimeter long. You now have a working flame.
This is where the fun begins. Run the flame over and around the join between the two metal pieces with the tip of the blue cone touching the metal. You should do this methodically and continuously, without stopping in any one particular spot. Once the metal around the join is glowing hot, it is time to actually braze. Using your free hand, grab the brazing stick at the top. Now, touch the bottom end of the stick to the join between the two metal pieces. Move the flame so that the tip of the blue cone is now resting on the brazing stick. As soon as you see the brazing stick begin to melt, start moving both it and the flame along the join in a swift, but sure, way. With practice, you will learn to spread a thin layer of braze along the join in this way. Once you have covered the length of the join with braze, remove the brazing stick and focus the flame on the now congealing braze: this will help to even it out, eliminating lumps. Now, turn off your torch. Do this by first completely closing the oxygen valve and then, after that, completely closing the acetylene valve. Closing the acetylene valve first will lead to a loud and startling pop, so always shut off the oxygen first. Now, place the torch in a safe and cool place. If there are more joinings to be brazed that you couldn't access before, use the tongs to move your metal pieces into position for the new work. SAFETY NOTE: You will receive serious burns from touching hot metal. Always use tongs to manipulate your work after you have heated it up. Repeat the above process again, starting from lighting the torch, as many times as necessary until you have brazed all of the joinings.
Once you are finished brazing, it is necessary to clean up. First, turn the valves on the gas cylinders to the completely shut position. Your cylinder and regulator gauges should maintain their previous pressures. Now, open the valves on the torch, one at a time, to flush the gasfrom the lines between the cylinders and the torch. While doing this, you should notice the pressure readings on the regulator and cylinder gauges drop rapidly down to zero. The cylinder gauge will drop first while the regulator gauge stays put. Don't worry about this; the regulator gauge will eventually decrease too. Now that you have flushed the lines of gas, adjust the regulators to 0 psi so that no gas may escape through them. Also, make sure that the valves on the torch are in the off position. SAFETY NOTE: Make sure that the gas cylinders always remain upright and well anchored. If a cylinder should fall, the cap may snap, turning the cylinder into a rocket with enough force to blast through a cement wall.
You have now completed a successful brazing operation that will join two pieces of metal together without the hassle and difficulty of welding.